Gen Chem

65問 • 2年前

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is obtained by comparing a quantity with a standard unit. For weight, the standard unit is Kilogram (Kg) • For length, centimeters (cm) or inches (in). • All ____ are subject to uncertainty • The choice of the correct instrument for measurement: the concept of accuracy and precision. • "accurate" and "precise" • used to describe measurements • often interchanged but have different meanings

Measurement

The closeness of a measurement to the true or accepted value.

Accuracy

the degree of agreement between successive measurements using a given insunment (how close measurements and to each other)

Precision

a good visualization of accuracy and precision - Precision is not dependent on accuracy - A set of measurements can be very precise but not accurate.

Darts

the difference between the highest and lowest valves off measurements - to determine the precision of multiple sets of datas

Range

is anything that occupies space and has mass

Matter

General Properties of Matter

• mass • weight • volume • density • specific gravity

is the amount of matter in an object • The more matter is present in an object means the greater its ___ • It is usually expressed in grams (g) or kilograms (kg) • Materials that are compact have relatively greater ___ than those with a hollow interior.

Mass

is the measure of force that acts on an object • It is expressed as the amount of matter (mass) multiplied by the gravitational force that acts on it. • The greater the gravitational force that acts on an object, the heavier it weighs. • it is expressed in newton(N)

Weight

are often interchangeable, but these are two different quantities"

Mass vs Weight

is the amount of space occupied by matter • It is expressed in liters (L) for liquids, or cubic meter (kg/m3) or grams or grams per cubic meter (g/cm3) • It tells us how compact it is • Greater the mass = more compact

Volume

is the ratio of a substance's density to a standard substance • Also known as relative density • Also known as dimensionless quantity

Specific Gravity

GRAVITY MEASUREMENTS:

9.8mp/s

Physical Properties

Melting point Boiling point Freezing point Solubility Metallic properties size texture shape color

is the temperature at which solid matter changes to liquid. It varies according to its composition of materials

Melting Point

it is the temperature at which a liquid turns into a solid matter.

Freezing Point

It is the temperature at which liquid evaporates

Boiling Point

it is the ability of a solute to dissolve in a given solvent.

Solubility

These are the different qualities that are observed specifically in metals

Metallic Properties

It is the ability of a material to allow heat or electric charges to pass through easily.

Conductivity

It is the ability of a material to be flattened into thin sheets.

Malleability

It is the ability of a material to be easily drawn into wires.

Ductility

- Atoms are dense and solid, with no internal structure or subatomic particles considered

Solid Sphere Model (John Dalton 1766-1844)

the mass to charge ratio obtained by jj thomson was ____ where c stands for coulomb the unit of electrical charge

1.76 X 10⁸c/g

was able to quantify the charge of the electron in his oil drop experiment in 1906 he use a fine ionized oil with electromagnetic force

robert millikan

A -? X Z

atomic mass

are not indivisible and are made up of three subatomic particles the protons neutron electrons

atoms

A X Z -?

Atomic number

used for more complex molecules such as organic compound those containing carbon bonds

Structural Formula

what are the three subatomic particles of atoms

protons neutron electron

atoms connected to a specific represented like molecular formula

condensed structural compound

are responsible for almost all chemical properties and reactivities of substances

electrons

hydrogens attached to each carbon will not be drawn: implicit hydrogen

Skeletal or line angle formula

which contains the protons and the neutrons are unchanged in chemical reactions but change in energy driven nuclear reactions

nucleus

formula of getting the neutron

n = a - z

prefix mono is never used in naming the first element of a covalent compound

Unwritten rule

formula of getting the proton

p = a - n

introduced the concept of phlogiston

Georg Ernst Stahl

is a universal component of fire that came from a Greek word inflammable - According to this theory,metal calx, when heated with charcoal, produces metal, in this reaction he explained that ___ of charcoal had united with calx

Phlogiston

formula of getting the electron if there is a charge on an element

q - p = e

also referred to in most references as the proton number(p) represents the total number of protons present in an element

atomic number

made the first breakthrough in the study of chemical reaction Due to his curiosity about the study of combustion and the concept of phlogiston he first tried to burn phosporus and sulfur.in his experiment both gained weight which resulted in both elements gaining weight

Antoine Lavoiser

being the tiniest and most mobile of all subatomic particles can easily be removed out of an atom or capture from an external source a removed or captured in an atom it becomes charged and is transformed to an ion

electrons

- in June 1738, lavoiser reacted oxygen with inflammable air obtaining "water in a very pure state" - he conducted that water was not an element but a compound of oxygen and inflammable air,hydrogen as it is known - Lavoiser explained the phenomenon in his famous textbook that imentaire de chimie that " in every operation,an equal quantity of matter exist both before and after the operation" this concept was also known as

Law of Conservation of Mass

since electrons are negatively charged the removal of electrons produces positively charged ions called

cation

a french chemist proposed the law of constant composition

Joseph Proust

atoms that gain electrons from external sources become negatively charged ions called__, also have more electrons than proton

anions

stated that if a pure compound is broken down into its consituent elements, the masses of the constituents will always have the same proportion

Law of Constant Composition

is determined as the difference between the number of protons and the number of electrons

charge number

he studied gases and gaseous mixtures under different external conditions -he noted that mathematically discrete manner in which elements combined to form different compounds

John Dalton

british chemist and physicist post the solid sphere model in the early 19th century shifted from philosophical ideas to scientific theory first atomic model based on experimental evidence and quantitative observations pave the way for the development of modern atomic theory

john dalton

which states that when two elements from a series of compounds, the masses of are that combine with a fixed mass of the other are in the ratio of (small) integers to each other

Law of Multiple Proportions

according to this theory atoms are tiny balls that can't be broken and all made of the same material this theory help explain how different chemicals mixed together and what makes them different

solid sphere model

english physicist known for his work on the nature of electrons propose the plum pudding model in the late 19th century discover the electrons as distinct particles understanding from indivisible atom to subatomic particles paved the way for for the exploration of atomic structure

jj thomson

according to this theory atoms are like ______ with tiny positive charges rather through out a cloud of negative electrons this theory help explain why atoms have a neutral charge overall and white day emit light when they collide with each other

plum pudding model

new zealand born physicist known for his contribution to nuclear physics introduce the nuclear model in the early 20th century first model to propose a central massive nucleus explain the behavior of positively charged alpha particles in the gold foil experiment laid the ground work for understanding atomic structure and radioactivity

ernest rutherford

according to the theory atoms of a nucleus with a positive charge and most of the mass surrounded by natural gas orbits like planets it explains why particles can pass through or bounds of atoms and is the basis of our current understanding of atomic structures

nuclear model

danish physics known for his pioneering work in atomic structure propose the planetary model in the early 20th century explain the atomic spectra with the precision introduce the concept of quantized energy levels bridge classical physics with emerging quantum mechanics

niels bohr

according to this theory electrons orbit the nucleus of an atom in specific energy levels or shells this theory help explain why atoms emit light and why they absorb certain colors of light it also help explain the stability of atoms and why they don't fall apart

planetary model

austrian physicist renowned for his contributions to quantum mechanics propose the quantum model in the 1920s quantum mechanics provides a comprehensive understanding of electron behavior it successfully explains multi electron atoms quantum mechanics is the foundation of modern atomic theory

erwin schrödinger

according to this theory electrons exist as a probable wave like pattern around the nucleus not in a specific orbit it explains why electrons act like a particles and wave and is the foundation of our understanding of atomic structure and widely used in modern physics

quantum model

most common way to represent molecules •symbols of each element are written down with a subscript indicating how many atoms are in the compound

Molecular Formula

gives the simplest whole number ratio of each element in a compound

Empirical Formula

all bonds and atoms are shown

Complete structural formula

better estimate of actual molecule shape bonds represented by sticks in previous model is cut short to give better representation

Space-Filling Model